WMOD00299

• Title: Physical Structure of Northern Colorado River Basin Cloud Systems
• Date: 9/1/1985
• State: CO
• Weather Modification - Doc Type: Report

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CHAPTER III

THE WATER PHASE.......................................... 62

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1. Temporal variations of the supercooled water field.................62

A. Case studi es. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

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(1) Pre-frontal and frontal cloud systems.......................63
a. Case study: 22 January 82...............................63
b. Case study: 15 December 81...............................71
c. Case study: 30 December 81...............................81
(2) Post-frontal cloud systems..................................88
a. Case study: 21 December 81...............................88
b. Case study: 13 December 81...............................95
c. Case study: 27 January 82..............................101
Orographic sys tams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

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(3)

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a. Case study:
b. Case study:
c. Case study:

14 December 81..............................107
16 December 81..............................112
13 January 82..............................115

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B. Discussion.................................................... .122

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(1) Pre-frontal and frontal cloud systems......................122
(2) Post-frontal cloud systems.................................125
(3) Orographic cloud systems...................................128
2. Physical and microphysical structure of the supercooled

wa ter field...................................................... .129

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A. Liquid water distribution......................................130
(1) Cloud top......................... .,................ . ..... .. .130

( 2) Cloud base........................ ~ . . . . . . . . . . . . . . . . . . . . . . . .137

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(3) Regions of strong orographic forcing.......................141

B. Microphysical characteristics..................................143
3. Comparison with other locations...................................148

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CHAPTER IV

TIlE ICE PH.ASE...........................................1 57

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1. General characteristics of the ice phase..........................157

A. Crystal concentrations.........................................157

B. Crystal habits................................................ .160

(1) Surface measurements.......................................160

(2) Aircraft measurements..................................... .167

a. 15 December 81......................................... .167

b. 21 December 81..........................................174

c. 5 January 82...........................................174

d. 23 January 82.......................................... .175

e. 31 January 82...........................................176

C. Precipitation rates. .. ......... .. ... ... .. ... ... ............... .176
2. Growth by vapor deposition........................................178
A. Dendritic snowfall events......................................179
(1) Characteristics of the dendritic growth region in shallow

cloud systems............................................. .180

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(2) Trajectories of dendritic crystals in shallow storms.......184
(3) Dendritic snowfall from deep storms........................l86
B. Cold temperature crystals.......................................188
C. Warm temperature crystals......................................191
3. Ice nuclea t1on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194
A. Review of DeMott et. ale (1986)................................194
B. 21 December 81 case study......................................I97
C. Surface measureD1ents........................................... 201

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